June to August - Pinus ponderosa cones
I usually collect my pine cones for crafts any time during the summer. The best times are soon after they ripen and fall, as they sometimes get trampled and damaged by animals or traffic. If you have a good place where there is little disturbance, this is where the most well formed cones will be.
I check frequently on my walks, and as soon as I see a good selection of nice, undamaged ones (avoiding last years crop, as these can be starting to deteriorate and rot) I'll start collecting.
They do best if they are collected in a large onion sack, or burlap, as this gives them a chance to completely dry out. Don't, whatever you do, store them where mice or squirrels can get at them as they'll destroy them getting the seeds out.
It's best to actually put them on a metal tray and put them in a lukewarm oven, as they will open to release the seeds. Use these as bird feed for the winter by rolling a suet ball in them. The birds love them, especially Chickadees.
Once they're open and most of the seeds have fallen out, store the cones in paper bags if possible, or a cardboard box.
I make Christmas wreaths, and other seasonal decorations with my cones, or simply display them in a rustic bowl or basket for a fireside accent.